Device and a method for reducing the number of exterior parasites on fish

Abstract

A device for reducing the number of exterior parasites on fish, comprising a hollow cylindrical filter member ( 3 ) having an inlet and an outlet, the circumference of the inlet and/or outlet being provided with a nozzle ( 1 a, 1 b ), wherein the nozzle comprises a substantially annular slit along the circumference of the inlet and/or outlet for ejecting a fluid towards the interior of the cylindrical filter ( 3 ).

The invention claimed is: 
     
       1. A device for reducing the number of exterior parasites on farmed fish, the device comprising:
 a hollow cylindrical filter member having a circumference and an interior, the hollow cylindrical filter member at an inlet end comprising an inlet with an inlet circumference and at an outlet end an outlet with an outlet circumference, the hollow cylindrical filter member being provided with holes between the inlet end and the outlet end, the holes allow exterior parasites to pass through the holes of the hollow cylindrical filter member while maintaining fish in the interior; 
 a first nozzle provided at the inlet end and having a substantially annular slit along the inlet circumference or a first nozzle provided at the outlet end and having a substantially annular slit along the outlet circumference for ejecting a fluid towards a first predefined point in the interior of the hollow cylindrical filter member between the inlet end and the outlet end. 
 
     
     
       2. The device according to  claim 1 , wherein the substantially annular slit is formed by 4 or more discrete nozzle members, each having a slit, wherein the discrete nozzle members are provided along the inlet circumference and/or the outlet circumference. 
     
     
       3. The device according to  claim 2 , wherein the first nozzle comprises two or more nozzle elements arranged in two or more levels displaced along a longitudinal axis of the hollow cylindrical filter member. 
     
     
       4. The device according to  claim 3 , wherein the discrete nozzle members of one of the nozzle elements at one level are off-set relative to the discrete nozzle members of another of the nozzle elements at another level. 
     
     
       5. The device according to  claim 1 , wherein the substantially annular slit is continuous. 
     
     
       6. The device according to  claim 5 , wherein the first nozzle comprises two or more nozzle elements arranged in two or more levels displaced along the axis of the hollow cylindrical filter member. 
     
     
       7. The device according to  claim 6 , wherein the discrete nozzle members of a nozzle element of at one level are off-set relative to the discrete nozzle members of a nozzle element at another level. 
     
     
       8. The device according to  claim 1 , further comprising a housing encasing the hollow cylindrical filter member and connected to the inlet and the outlet, providing a substantially fluid tight connection. 
     
     
       9. The device according to  claim 8 , further comprising a draining conduit provided in the housing, said draining conduit having at least one opening arranged to receive the parasites. 
     
     
       10. The device according to  claim 1 , wherein the first nozzle defines an angle of ejection in the range of 10 degrees and 60 degrees relative to a longitudinal axis of the hollow cylindrical filter member. 
     
     
       11. The device according to  claim 1 , further comprising a second nozzle having a substantially annular slit along the inlet circumference or along the outlet circumference not occupied by the first nozzle, wherein the substantially annular slit of the second nozzle is provided for ejecting a fluid towards a second predefined point of the hollow cylindrical filter member. 
     
     
       12. The device according to  claim 11 , wherein the second nozzle comprises a number of discrete nozzle members forming the substantially annular slit, each nozzle member having a slit, wherein the discrete nozzle members are provided along the inlet circumference or along the outlet circumference not occupied by the first nozzle. 
     
     
       13. The device according to  claim 12 , wherein the first nozzle comprises two or more nozzle elements arranged in two or more levels displaced along a longitudinal axis of the hollow cylindrical filter member. 
     
     
       14. The device according to  claim 13 , wherein a discrete nozzle member of one of the nozzle elements at one level is off-set relative to a discrete nozzle member of another of the nozzle elements at another level. 
     
     
       15. The device according to  claim 11 , wherein the first and the second predefined points are provided at different locations in the hollow cylindrical filter member. 
     
     
       16. The device according to  claim 1 , wherein said substantially annular slit has a width between 0.01 mm and 2 mm. 
     
     
       17. The device according to  claim 1 , wherein the fluid is air or water or air and water. 
     
     
       18. A device for reducing the number of exterior parasites on farmed fish, the device comprising:
 a hollow cylindrical filter member having a circumference and an interior, the hollow cylindrical filter member at an inlet end comprising an inlet with an inlet circumference and at an outlet end an outlet with an outlet circumference, the hollow cylindrical filter member being provided with holes between the inlet end and the outlet end, the holes allow exterior parasites to pass through the holes of the hollow cylindrical filter member while maintaining fish in the interior, the inlet circumference or the outlet circumference being provided with a first nozzle; 
 wherein the first nozzle has a substantially annular slit along the inlet circumference and/or along the outlet circumference for ejecting a fluid towards a first predefined point in the interior of the hollow cylindrical filter member between the inlet end and the outlet end; 
 wherein the hollow cylindrical filter member comprises a number of rods around the circumference of the hollow cylindrical filter member, the rods are arranged so as to be parallel to and spaced apart from each other so that spaces exist between the rods, the spaces providing the holes of the hollow cylindrical filter member.